NOS2 and diabetes mellitus: Furthermore, we found that i.t. administration of mouse recombinant IGF-1 (rIGF-1) as well as i.t. or i.p. treatment with EGCG alleviated the diabetes-induced pain-like behaviors, reduced neuroinflammation (suppressed IL-1β, TNF-α, and Iba-1+ microglia), prevented the M1 microglia polarization (less iNOS+Iba-1+ microglia), and restored the microglial IGF-1 expression.